Assessment of risk of bias in included studies
Two review authors will assess the methodological quality of the
included studies independently using the Cochrane Collaboration
tool for assessing risk of bias (Higgins 2011a). If they are not in
agreement, a third review author will be consulted.This tool covers
six specific domains namely; sequence generation, allocation
concealment, blinding of participants and outcome assessors, incomplete
outcome data, selective outcome reporting and other issues
(see Appendix 2). We will assess blinding and completeness
of outcome data for each outcome separately.